Voltage output digital-to-analog converter circuit

Abstract

According to this invention, there is provided a voltage output digital-to-analog converter circuit, including other ones of the second resistive elements and third resistive elements having a desired resistance value are series-connected between the other ends of the second resistive elements, which are connected to switching elements of the plurality of switching elements to which a most significant bit and a least significant bit are supplied, and the ground.

1. A voltage output digital-to-analog converter circuit, comprising:
 a plurality of switching elements provided corresponding to respective bits of an input digital signal to switch connection states of the plurality of switching elements to either the reference voltage terminal or the ground terminal according to the bits of the input digital signal; and 
 a resistor network which includes first resistive elements and second resistive elements having a resistance value twice a resistance value of the first resistive elements and in which one ends of the second resistive elements are connected to the plurality of switching elements respectively, the first resistive elements are connected between neighboring pairs of the other ends of the second resistive elements respectively, and other ones of the second resistive elements and third resistive elements having a desired resistance value are series-connected between the other ends of the second resistive elements, which are connected to switching elements of the plurality of switching elements to which a most significant bit and a least significant bit are supplied, and the ground. 
 
   
   
     2. The voltage output digital-to-analog converter circuit according to  claim 1 , wherein
 each of the switching element is formed by connecting a source of first transistor and a source of second transistor to the reference voltage terminal and the ground terminal respectively and connecting the one end of the second resistive element to a junction point of the drain of first and second transistors. 
 
   
   
     3. The voltage output digital-to-analog converter circuit according to  claim 2 , wherein
 the first and second transistors are formed such that resistance values of on-resistance are equal to each other. 
 
   
   
     4. The voltage output digital-to-analog converter circuit according to  claim 2 , wherein
 the first transistor is composed of a PMOS transistor, and the second transistor is composed of an NMOS transistor. 
 
   
   
     5. The voltage output digital-to-analog converter circuit according to  claim 1 , wherein
 each of the third resistive element has a resistance value which is 2/3 times a resistance value of on-resistance of the plurality of switching elements. 
 
   
   
     6. The voltage output digital-to-analog converter circuit according to  claim 1 , wherein
 each of the third resistive element is a third transistor which has an on-resistance having a resistance value 2/3 times a resistance value of on-resistance of the plurality of switching elements. 
 
   
   
     7. The voltage output digital-to-analog converter circuit according to  claim 6 , wherein
 the third transistor is composed of an NMOS transistor. 
 
   
   
     8. The voltage output digital-to-analog converter circuit according to  claim 6 , wherein
 a voltage equal to a voltage applied to the gate of second transistor is always applied to a gate of the third transistor, and thereby the third transistor is set to be on. 
 
   
   
     9. The voltage output digital-to-analog converter circuit according to  claim 6 , wherein
 each of the switching element is formed by connecting a first transistor and a second transistor to the reference voltage terminal and the ground terminal respectively and connecting the one end of the second resistive element to a junction point of the drain of first and second transistors. 
 
   
   
     10. The voltage output digital-to-analog converter circuit according to  claim 9 , wherein
 the third transistor is formed to have an aspect ratio which is 3/2 times an aspect ratio of the second transistor. 
 
   
   
     11. The voltage output digital-to-analog converter circuit according to  claim 1 , further comprising
 an amplifier connected to a junction point of the second resistive element connected to the switching element, to which the most significant bit is supplied, and the first resistive element. 
 
   
   
     12. A voltage output digital-to-analog converter circuit, comprising:
 a plurality of switching elements provided corresponding to respective bits of an input digital signal to switch connection states of the plurality of switching elements to either the reference voltage terminal or the ground terminal according to the bits of the input digital signal; and 
 a resistor network which includes first resistive elements and second resistive elements having a resistance value twice a resistance value of the first resistive elements and in which one ends of the second resistive elements are connected to the plurality of switching elements respectively, the first resistive elements are connected between neighboring pairs of the other ends of the second resistive elements respectively, and other ones of the second resistive elements and correction transistors each having an on resistance with a desired resistance value are series-connected between the other ends of the second resistive elements, which are connected to switching elements of the plurality of switching elements to which a most significant bit and a least significant bit are supplied, and the ground. 
 
   
   
     13. The voltage output digital-to-analog converter circuit according to  claim 12 , wherein
 each of the switching element is formed by connecting a source of first transistor and a source of second transistor to the reference voltage terminal and the ground terminal respectively and connecting the one end of the second resistive element to a junction point of the drain of first and second transistors. 
 
   
   
     14. The voltage output digital-to-analog converter circuit according to  claim 13 , wherein
 the first and second transistors are formed such that resistance values of on-resistance are equal to each other. 
 
   
   
     15. The voltage output digital-to-analog converter circuit according to  claim 13 , wherein
 the first transistor is composed of a PMOS transistor, and the second transistor is composed of an NMOS transistor. 
 
   
   
     16. The voltage output digital-to-analog converter circuit according to  claim 12 , wherein
 each of the correction transistor has an on-resistance having a resistance value which is 2/3 times a resistance value of on-resistance of the plurality of switching elements. 
 
   
   
     17. The voltage output digital-to-analog converter circuit according to  claim 12 , wherein
 the correction transistor is composed of an NMOS transistor. 
 
   
   
     18. The voltage output digital-to-analog converter circuit according to  claim 13 , wherein
 a voltage equal to a voltage applied to the gate of second transistor is always applied to a gate of the correction transistor, and thereby the correction transistor is set to be on. 
 
   
   
     19. The voltage output digital-to-analog converter circuit according to  claim 13 , wherein
 the correction transistor is formed to have an aspect ratio which is 3/2 times an aspect ratio of the second transistor. 
 
   
   
     20. The voltage output digital-to-analog converter circuit according to  claim 12 , further comprising
 an amplifier connected to a junction point of the corresponding second resistive element connected to the switching element, to which the most significant bit is supplied, and the corresponding first resistive element.